Leukonychia is a nail disorder characterized by the visible whiteness appearing in a person's fingernails or toenails, notes John Hopkins University. Individuals may develop the disorder due to trauma, drugs or infectious or metabolic diseases.
Different types of leukonychia, including leukonychia totalis, leukonychia striata, leukonychia partialis and leukonychia punctata, can affect the entire nail or part or the nail and can cause white spots or crossing bands across the nail, explains John Hopkins University. In rare cases, individuals can inherit this nail disorder. A 2011 study verifies the existence of hereditary leukonychia demonstrated by whiteness on all 20 nails of each family member of four Pakistani families.